1. Field
Secondary system usage in a wireless network may be related to opportunistic usage of radio resources/spectrum of a primary system or cognitive radio operation. The primary system could be, for example, conventional cellular communication, such as, for example, a Long Term Evolution A (LTE-A) network. In other words, a secondary system or secondary users may utilize spectrum of primary system opportunistically, but may be constrained by the secondary system not being permitted to degrade performance or interfere excessively with the primary system.
2. Description of the Related Art
LTE-A describes a multicarrier system in which each cell has a primary component carrier and several secondary component carriers. Each cell in LTE-A may automatically select one of the component carriers as its primary carrier when eNB is powered on. Further, each cell may dynamically select additional component carriers for transmission/reception as well when the traffic load increases, but taking into account the caused interference on neighbor cells before activating new component carriers. The component carrier usage, however, is an open item and may be changed. Thus, this description is simply one example of an LTE-A system.
As a result, there can be a dynamic behavior of activations and de-activations of component carriers by evolved Node-Bs (eNBs) in the LTE-A system. In the LTE-A system the eNBs may control cells. Thus there may be muted (spatially unused spectrum) component carriers in cells that could be utilized for the secondary usage of radio resources, such as for direct device-to-device (D2D) communication or some other local communication scheme (sensor networks, local mobile-to-mobile (M2M) communication, etc.).